Sulphonamido monoazo dyestuffs



Patented July 11, 1944 UNITED STATES PATENT OFFICE SULPHONAMIDO' MON OAZO D'YESTUFFS Oscar Knecht and Theodor Wirth, Basel, Switzerland, assignors to Sandoz Ltd, Frihourg,

Switzerland, a firm N Drawing. Application July 13, 1942, Serial No. 450,794. In Switzerland July 11, 1941 4 Claims.

dyestuffs can be prepared by coupling a diazotized aminobenzene sulphonamide of the formula SOa-NELC 0 CH3 wherein X stands for hydrogen and methyl with arylpyrazolone sulphonic acids.

The aminobenzene sulphonamides of the above formula, in which one hydrogen of the sulphamide group is replaced by an acetyl group and which are used according to the present invention, are intermediate products which have not been used for the manufacture of dyestufis.

The monoazo dyestuffs obtained fromthese intermediates dye wool and silk from an acid bath in greenish yellow shades of excellent fastness to light. As compared to the known pyrazclone dyestufis described in the U. S. A. specification No. 1,876,884 and prepared from such diazotized aminobenzene sulphonamides in which one hydrogen atom of the sulphonamide group is replaced by an aryl nucleus, the new dyestuffs possess better levelling properties and a better stability to alkali.

The following examples, without being limitative, illustrate the present invention, the parts being by weight:

Example 1 214 parts of metanilic acid acetyl amide of M. P. 152 C. which can be prepared, for example, by acetylation of meta-nitrobenzene sulphonamide and subsequent reduction, are diazotized in the usual way. The solution of the diazo compound is then added to an aqueous solution of 323 parts of 1-(2':5'-dichloro-4'-sulphophenyl) -3methyl-5-pyrazolone containing sodium acetate. When the coupling has completed, the dyestufi is salted out and filtered. In dry state it is a yellow powder dyeing wool from an acid bath in clear greenish-yellow shades. The dyeings possess excellent fastness to light, excellent levelness and very good fastness to alkali.

The formula of the new dyetuff isthe following one:

I Cl C=N I SO2NH-COCH3 /N SOaH N= =C C1 OH By using instead of the above mentioned pyrazolone an equivalent quantity of 1-(4-chloro- 2-sulphophenyl) 3-methyl-5pyrazolone, a dyestuif will be obtained with similar shade and properties.

Example 2 =N s OzNlELC 0 CH3 /N -s 0311 By using instead of the above cited pyrazolone 288.5 parts of l-(2-chloro-5'-sulphophenyl)3-methyl-5-pyrazolone, a dyestuff with similar shade and properties will be obtained.

What We claim is:

1. The monoazo dyestuffs of the general formula I O N wherein X stands for a member of the group consisting of hydrogen and methyl, A and B each stand for a member of the group consisting of hydrogen and halogen and C stands for being a yellow powder, dyeing animal fibres in bright yellow shades of excellent fastness properties.

3. The monoazo dyestufi of the formula 15 being a yellow powder, dyeing animal fibres in bright yellow shades of excellent fastness properties.

4. The monoazo dyestuff of the formula SO2NHO 0 CH3 being ayellow powder, dyeing animal fibres in bright yellow shades of excellent fastness properties.

OSCAR KNECHT. THEODOR WIRTH. 

